1. Field of the Invention
The present invention generally relates to rotary machines such as steam turbines or compressors. More specifically, the present invention relates to inhibiting adhesion of fine particles contained in air or gas to parts of a rotary machine.
2. Description of the Related Art
Steam turbines include moving blades and stationary blades. A steam turbine is driven by blowing a jet of working fluid such as steam onto the moving blades. Therefore, parts of a steam turbine such as moving blades and stationary blades come in direct contact with a working fluid.
Compressors are used to compress various types of gases in chemical plants. A compressor includes a rotatable impeller, and the impeller is rotated with the help of power received from outside of the compressor to compress a gas. Therefore, even in a compressor, parts such as an impeller and a diffuser come in direct contact with the gas.
The working fluids used in steam turbines or the gases compressed by compressors contain fine particles of silica, iron oxide, or hydrocarbon. When these particles come in contact with the parts of a steam turbine or a compressor, they get adhered to those parts and corrode those parts. As a result, the efficiency of the steam turbine or the compressor is reduced.
Japanese Patent Laid-Open Publication No. H7-40506 teaches to coat the parts of the steam turbines or the compressors with fluorocarbon resin to prevent corrosion of the parts by the fine particles. However, some parts of the steam turbines or the compressors rotate while other parts are stationary. For example, the moving blades of the steam turbines and the impellers of the compressors rotate. Even if the moving parts are coated with fluorocarbon resin, a centrifugal force acts on the rotating parts and weakens the anticorrosive action of the coat of the fluorocarbon resin. Thus, there is a need for a technology that can surely protect the rotating parts of steam turbines and compressors from the fine particles.